Amazon Rainforest Flashcards
Amazon Key Facts
6.7m km^2 - 60% in Brazil
Population of 30m - 350 ethnic groups
10% of world’s species
11,500 km^2 deforested each year - 2022
17% already lost
400b trees - 20% of carbon in earth’s biomass
15% of world’s freshwater
3000mm of rainfall per year
Average temperature of 28 Celsius - 25% of rainfall evaporated, 75% intercepted
Countries in the Amazon - location
South America: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Suriname, Guyana, French Guiana
Changing politics in the Amazon
2019-2023 - Bolsonaro didn’t replace IBAMA agents who protected against illegal logging. Increase in legal logging as he endorsed it
2003-19/2023 onwards - Lula - environmentalist but also popularist:
- pledge to end deforestation by 2030
- crackdown on illegal logging - 33% decrease (Jan. - Jul, 2023)
- 6 new preserves
Local impacts of deforestation - Amazon
No trees - no water uptake from the soil - soy roots not as efficient as trees → decreased transpiration
No interception, not transpiration
Dry baked soils exposed to sun (increased evaporation → increased run-off will result in high risk of flooding
Forests emit salts + organic fibres which act as condensation nuclei - loss inhibits cloud formation
Water deficit due to increased water leaving the area → desertification
Global impacts of deforestation
‘Biological Pump’ - Amazon helps to drive atmospheric circulation round the globe
Increased CO2 in the atmosphere - global warming → changes to global precipitation patterns
Positive feedback in Amazon
Deforestation → decreased evapotranspiration → water leaves area through river rather than being recycled → less water vapour available in the atmosphere for precipitation so rain levels fall → further decreased evapotranspiration
Impacts of deforestation on Amazon carbon cycle - burning
Between 30-60% of carbon is immediately released back to the atmosphere when trees are burnt
In a typical year, Amazon absorbs 2.2b tonnes and releases 1.9b tonnes. However, its capacity to absorb carbon is decreasing
No photosynthesis until new plant growth begins + respiration (plant and animal) drops to almost zero as population falls
Rain washes ash into the ground, high carbon content where it can be washed away - leaching
Estimated store between 80-120b tonnes of Carbon around the world
↑ increased biomass due to high sequestration of CO2 - acts as negative feedback:
↑ CO2 encourages biomass growth but also mean they die sooner. New trees take 20 years of growth to reach similar CO2 absorption rates
Impacts of deforestation on Amazon carbon cycle - farming
Replacing deforested land with farmland means there is still a carbon cycle but it is nowhere near the same scale as the rainforest
Carbon cycle in Amazon
Respiration by plants, trees + animals return CO2 back to the atmosphere
Decomposition thrives in humid conditions
Leaf litter accumulates and form deep layers of peat
Some Carbon stored within the soil
Variation in the Amazon river regime - deforestation
~ 50% of the rain in the Amazon does not reach the river as it is intercepted by the canopy and then transpired back into the atmosphere
When trees are deforested, the top soil is removed due to the heavy rain which further ↓ infiltration and throughflow
Therefore, ↑ surface run-off → ↑discharge and flash flooding
Variation in the Amazon river regime - seasonal changes
Rainy season can cause the Amazon to rise by nearly 40ft
This water needs to go somewhere, and it spreads out and floods much of the forest. So the trees, plants and animals have learned to adapt to flooding
Variation in the Amazon river regime - agriculture (land-use changes)
62% of land cleared in the Amazon is for agriculture
Crops often intercept less precipitation than natural vegetation.
Cows compact the ground, increasing surface flow + ↓ infiltration
Variation in the Amazon river regime - mining
Carajás mine in Northern Brazil is the world’s longest mine at almost 1000km long
Leads to large scale vegetation clearance which ↓ evapotranspiration + convectional rainfall. Loose top soil layer will get washed into the river, reducing capacity
Mitigation of human impacts in the Amazon - national and international agreements
FSC - forest stewardship council
USA cancel debt for Brazil to protect rainforest
“Amazonian NATO” - ACTO
- Amazon Cooperation Treaty Organisation, promote sustainable development, 8 countries, reverse loss of rainforest cover worldwide
TARAPOTO process to help achieve harmonious forest development (1995) - policy makers from 8 countries identified 12 criteria to manage rainforest:
- investment in education + research
- policies and legal framework
Creation of national parks - Jau National Park and Para Rainforest Reserve is larger than England
Mitigation of human impacts in the Amazon - local
Reforestation - replacing trees - slow - not very effective
Agroforestry - planting crops between the trees
